Engine valve for fluid-operated pump



Jan. 29, 1963 c. J. COBERLY I 3,075,554

ENGINE VALVE FOR FLUID-OPERATED PUMP Original Filed Dec; 2, 1955 a Sheets-Sheet 1 .yrveers; Mean, .73 usssu. 8: 16 521v Jan. 29, 1963 c. J. COB ERLY 3,075,554

ENGINE VALVE FOR FLUID-OPERATED PUMP Original Filed Dec. 2, 1955 8 Sheets-Sheet v2 Ma. 51 Jim? 6? v 17:627-

Alike/s, M Russia 6=KEN Jan. 29, 1963 c. J. COBERLY 3,075,554

ENGINE VALVE FOR FLUID-OPERATED PUMP Original Filed Dec. 2, 1955 8 Sheets-Sheet 3 L'LmeEA/cE (I 'aeseqg, jvvewrae.

By Ms ,4rmen s.

Ema/s, 17/56, Russsu fidfiamv c. J. COBERLY 7 3,075,554

ENGINE VALVE FOR FLUID-OPERATED PUMP 8 Sheets-Sheet 4 Jan. 29, 1963 Original Filed Dec. 2, 1955 By Ms lrraeusys.

.Zfi'wms, Elsa/J3 ussaLafdz/wv Jan. 29, 1963 c. J. COBERLY ENGINE VALVE FOR FLUID-OPERATED PUMP 8 Sheets-Sheet 5 (riginal Filed Dec. 2, 1955 CZAZENCE d Cass/e1- y,

5y #wXrmQA/E S mew, fire-cm Russsu. a; JdER/v Jan. 29, 1963 c. J. COBERLY 3,075,554

ENGINE VALVE FOR FLUID-OPERATED PUMP Original Filed Dec. 2, 1955 8 Sheets-Sheet 6 I flex/a 624255265 cl L'aaeezy,

IvrEA/raa.

.ByMs ,lrmemzys.

Aime/. Ids-aw, RUSSELL & K E 21v Jan. 29, 1963 c. J. COBERLY 3,075,554

ENGINE VALVE FOR FLUID-OPERATED PUMP Original Filed Dec. 2, 1955 8 Sheets-Sheet 7 United States Patent California Original application Dec. 2, 1955, Ser. No. 550,538, now Patent No. 2,935,953, dated May 10, 1960. Divided and this application Mar. 7, 1960, Ser. No. 13,369

7 Claims. (Cl. 137622) This application is a division of my copending application Serial No. 550,538, filed December 2, 1955, now Patent No. 2,935,953, granted May 10, 1960.

The present invention relates in general to fluidoperated bottom hole pumps for oil wells and, more particularly, to a novel engine valve for controlling the fluid-operated engine section of such a pump.

An important object is to provide a fluid-operated pump having its engine valve intermediate its engine and pump sections and having an engine valve which includes a valve member encircling and controlled by a rod connecting engine and pump plungers. A related object is to provide a valve member which is hydraulically movable between its operating positions to effect the strokes of the engine plunger, and to provide a connecting rod between the engine and pump plungers which acts as a pilot valve for controlling the application of fluid pressure to the valve member to move it between its operating positions.

. Another object is to provide a fluid-operated pump in which a rod interconnecting engine and pump plungers is slidable in a tubular valve member of the engine valve, and wherein the valve member is slidable on the rod in one direction to produce movement of the engine and pump plungers in such direction and is slidable on the rod in the opposite direction to produce movement of the engine and pump plungers in the opposite direction. With this construction, the valve member always moves in the same direction as the rod, except at the ends of the working and return strokes, so that friction between the rod and the valve member constantly biases the valve member toward its proper operating position, which is an important feature.

-Another object is to provide a single-acting pump having an engine valve which is located intermediate engine and pump sections of the pump, and which has a three-speed governing action during the working stroke of the pump and a single-speed action during the return stroke thereof.

Another object of the invention is to provide a fluidoperated pump having a differential-area engine valve intermediate engine and pump sections of the pump.

Another object of importance is to provide a differential-area engine valve including a tubular valve member having a uniform external diameter and a variable internal diameter to provide a plurality of pressure areas.

More particularly, an object is to provide a valve member of the foregoing nature having a uniform outside diameter and having two different diameters ad jacent the respective ends thereof, whereby to provide the valve member with a large annular area at one end thereof, a small, outer annular area at the other end thereof, and a small, inner annular area facing in the same direction as the outer annular area.

Another object of the invention is to provide a differential-area engine valve of the foregoing nature in which a valve rod extends through the valve member and has a diameter substantially equal to the smaller of the inside diameters of the valve members.

Another object is to provide a differential-area engine valve of the nature outlined in the preceding paragraph including a floating, tubular cylindrical member making a sliding fit with the valve rod and making a sliding fit with the larger of the inside diameters of the valve member, this floating member serving to separate the inner and outer annular areas of the valve member.

Another object is to provide a differential-area engine valve including a tubular valve member having a large annular area facing in one direction and smaller, inner and outer annular areas facing in the opposite direction and respectively exposed to different pressures, the inner and outer annular areas mentioned being provided by forming the valve member with different inside diameters and a substantially uniform outside diameter. A related object is to provide a differential-area engine valve wherein the large annular area is alternately exposed to the diiferent pressures mentioned, whereby to produce reciprocatory movement of the valve member.

Another object is to provide a fluid-operated pump having an engine valve intermediate motor and pump sections of the pump, the motor and pump sections including motor and pump plungers connected by a rod which is sealed by floating bushings encircling the rod between the engine valve and the engine and pump plungers.

Another important object of the present invention is to provide an engine valve having a component which includes inner and outer sleeves secured together with a fluid-tight fit therebetween, there being fluid passages in one of the sleeves at the interface between the sleeves, preferably formed by providing the inner sleeve with grooves in its exterior surface which are closed by the outer sleeve. The two sleeves may be secured together in a fluid-tight manner by pressing the inner sleeve into the outer, by shrinking the outer sleeves onto the inner, or the like.

Another object is to provide an engine valve having a two-sleeve component of the foregoing nature which constitutes a valve body for the tubular valve member hereinbefore discussed.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the art in the light of this specification, may be attained with the exemplary embodiment of the invention which is illustrated in the accompanying drawings and which is described in detail hereinafter. Referring to the drawings:

FIG. 1 is a vertical sectional view, on a reduced scale, illustrating the present invention as installed in a well;

FIGS. 2, 3 and 4 are enlarged, horizontal sectional views respectively taken along the arrowed lines 2-2 33 and 44 of FIG. 1;

FIGS. 5 and 6 are vertical sectional views respectively taken along the irregular arrowed lines 55 and 66 of FIG. 2. and taken at the same level;

FIG. 7 is a downward continuation of FIG. 5;

FIGS. 8, 9 and 10 are vertical sectional views respec tively taken along the irregular arrowed lines 8-8, 9-9 and 10-10 of' FIG. 3 and taken at the same level, FIG. 8 being a downward continuation of FIG. 7;

FIG. 11 is a vertical sectional view taken along the irregular arrowed line 11-11 of FIG. 4, and is a down ward continuation of FIG, 8;

FIGS. 12 and 13 are enlarged, fragmentary vertical sectional views respectively taken along the arrowed lines 1212 and 1313 of FIG. 8, FIG. 12 illustrating a pump piston means of the invention and FIG. 13 illustrating an engine valve thereof;

FIG. '14 is similarto FIG. 13, but illustrates various components of the engine valve in other operating positions;

FIGS. and 16 are fragmentary, enlarged, vertical sectional views respectively duplicating the upper and lower halves of FIG. 13;

IFIGS. 17, 18, 19 and are transverse sectional views respectively taken along the arrowed lines 17-17, 18-18, 19-19 and 20-20 of FIG. 15;

FIGS. 21 and 22 are horizontal sectional views respectively taken along the arrowed line 21-21 and 22-22 of FIG. 16; and

FIGS. 23 and 24 are simplified, diagrammatic views illustrating the operation of the fluid-operated pum of the invention and showing various components thereof in diflerent operating positions.

General Description Referring first to FIG. 1 of the drawings, the numeral 30 designates a casing set in a well bore 22, the lower end of the casing being shown perforated to admit production fluid from a productive formation 54. The casing 30 terminates at its upper end in a casing head 36 from which a tubing system 38 is suspended in the casing. The tubing system 38 supports a bottom-hole assembly 40 within the lower end of the casing 30, the bottom-hole assembly housing a fluid-operated singleacting free pump 42, FIG. 2 et seq., when this pump is in its operating position in the well. The pump 42 is supplied with operating fluid under high pressure through a supply or power oil tubing 44 which form part of the tubing system 33, this tubing system also including a power oil return tubing 46 through which spent operating fluid discharged by the pump 42 is returned to the surface. A production tubing 48 completes the tubing system 36 the production tubing performing the function of conveying the production fluid discharged by the pump 42 upwardly to the surface, and also performing the function of conveying the pump 42 between the surface and its operating position in the well. Since the tubing 48 is utilized to convey the pump 42 between its operating position and the surface, this tubing is the largest of the three tubings 44, 46 and 43, so that utilizing it as the production tubing as well minimizes productionfluid friction, which is a feature of the invention.

The tubing system 38 terminates at its upper end in a control device 50 having valve means, not specifically shown, for connecting the supply, return-and production tubings 44, 46 and 48 to supply, return and production pipes 52, 54 and 56, respectively, during operation of the pump. 42, the supply pipe leading to a suitable source, not shown, of operating fluid under high pressure, and the return and production pipes leading to suitable points of: disposal for the spent operating fluid and the production fluid. As will be discussed hereinafter in more detail, the aforementioned valve means of the control device 50 may be operated to reverse the flow through the return pipe 54 and the return tubing 46 to displace the pump 42 upwardly through the production tubing'43 to the. surface when it is desired to remove the pump from the well. The control device50 also provides means, such as valve means, not shown, for maintaining a fluid pressure differential between the fluid columns in thereturn and production tubings 46 and 48 to effect the return stroke of an engine and pump piston means 58 in the pump 42, the working stroke of the piston means being effected by operating fluid under pressure from the supply tubing, as will be discussed hereinafter. Preferably, the return stroke of the piston means 58 is produced by maintaining the pressure in the fluid column in the return tubing 46 higher than the pressure of the fluid column in the production tubing 48, as by applying a back pressure to the return tubing 46 by means of the control device.

Considering the pump 42 and the bottom-hole assembly 40 generally, the pump includes an upper, engine or motor section 60, FIG. 5, an intermediate engine valve 62, FIG. 8, for alternately supplying the fluid pressures in the supply and return tuhings 44 and 46 to the piston means 58 to alternately produce the working and return strokes thereof, and a pump section 64, FIGS. 8 and 11, for pumping production fluid from the well into the production tubing 48. The bottom-hole assembly 40 includes, generally, an upper sealing collar 66, FIG. 5, which receives the upper end of the engine section 60 of the pump 42, an intermediate sealing collar 68, FIG. 8, which receives the engine valve 62 located intermediate the engine and pump sections 60 and 64, and a lower sealing collar, or bottom shoe 70, FIG. 11, which receives the lower end of the pump section 64 of the pump.

The Bottom-Hole Assembly 40 Considering the bottom-hole assembly 40. in more detail, and taking upthe path followed by the operating fluid under pressure from the supply tubing 44 first for convenience, the supply tubing 44 is threaded at its lower end into the upper sealing collar 66, and communicates with the upper end of a longitudinal bore, not shown, through this sealing collar. Threaded into the lower end of the upper sealing collar 66 in communication with the aforementioned bore therethrough is a pipe 72, FIG. 9, which extends into a longitudinal bore 74 in the upper end of the intermediate sealing collar 68', and which is sealed relative to this sealing collar by an O-ring 76. Thus, operating fluid under pressure from the supply tubing 44 flows through the upper sealing collar 66 and the pipe 72 into the bore 74, and, from this bore, it flows through a passage 78 into a main bore 80 through the intermediate sealing collar 68. The enginevalve 62 of the pump 42 is disposed in the main bore 80 and provides an operating fluid intake 82 of the pump 42. At the ends of the main bore 80 through the intermediate sealing collar 68 are counterbores 84 and 86 into which are pressed sleeves 88 and 90, the pump 42 carrying O-rings 92 and 94 which engage the sleeves 88 and 90, respectively, when the pump is in its operating position to isolate the operating fluid intake 82 from all but the supply tubing 44.

Tracing the path of the spent operating fluid through the bottom-hole assembly 40 to the return tubing 46, the return tubing is threaded at its lower end into a bore 98, FIG. 6, in the upper end of the upper sealing collar 66.. This bore communicates through a passage with a longitudinal bore 102 in the upper sealing collar 66. The bore 102 communicates at its lower end with a passagev 104 which leads to a bore 106 in the upper sealing collar 66. Pressed into the bore 106 is a sleeve 112 which is engaged by O rings 114 on the pump 42, the lowermost O-ring 114 isolating the spent operating fluid from other fluids. Extending into the bore 106 in the upper sealing collar 66, and threadedly connected to the upper sealing collar, is a pump-housing tube 116, there being an an nular space 118 between the engine section 60 of the pump 42 and'the pump housing tube 116 which is in con-- stant communication with the return tubing 46 through the bore 106, the passage 104, the bore 102, the passage 100 and the bore 98. The annular space 118 communi-- cates with port means 120 in the pump 42, this port means, as hereinafter described, constantly applying the pressure in the return tubing 46 to the upper end of the piston means 58.

The annular space 118 between the pump 42 and the pump housing tube 116 extends downwardly into the intermediate sealing collar 68, the lower end of the pump housing tube 116, as shown in FIG. 8, being threadedly connected to and extending into a counterbore 122 in the upper end of the intermediate sealing collar. The engine valve 62 of the pump 42 is provided with a spentoperating-fluid exhaust 124 which communicates with the counterbore 122, the exhaust 124 thus constantly communicating with the return tubing 46 through the annular space 118, the bore 106, the passage 104, the bore 102, the passage 100 and the bore 98. The aforementioned O-ring 92 is located between the operating fluid intake 82 and the exhaust 124 for spent operating fluid, thereby separating these from each other.

The pressure in the return tubing 46 is also transmitted downwardly into the bottom shoe 70 for the purpose of unseating the pump 42 and moving it upwardly upon reversal of flow through the return tubing, as will be described in more detail hereinafter. For this purpose, the intermediate sealing collar 68 is provided with a passage 126, FIG. 10, which communicates with a longitudinal bore 128 in this sealing collar, the bore 128 communicating at its lower end with a passage 130 which communicates with a bore 132 in the lower end of the intermediate sealing collar. Threaded into the bore 132 is the upper end of a pipe 134 which, as shown in P16. 11, extends into the upper end of a longitudinal bore 136 in the bottom shoe 70. The lower end of the bore 136 communicates through a passage 138 with a counterbore 140 in the bottom shoe 70. At the upper end of the counterbore 140 is a short bore 142 and above this bore is a counterbore 144 into which is pressed a sleeve 146. An O-ring 148 on the pump 42 engages the Sleeve 146 to isolate the spent operating fluid in the counterbore 144 from other fluids.

Below the counterbore 144 is a counterbore 150 into which is pressed a seat 152 for a standing valve assembly 154 which includes a standing valve 156. The standing valve assembly 154 extends through a short bore 158 in the bottom shoe 70 into an inlet pipe 160 threaded into a counterbore 162 in the lower end of the bottom shoe. The standing valve assembly 154 is similar to that disclosed and claimed in my copending application Serial No. 487,303, filed February 10, 1955, now Patent No. 2,869,490, and, consequently, will be considered only generally herein.

The standing valve assembly 154 provides a tapered seat 164 for the pump 42, or, more specifically, for an inlet plug 166 at the lower end of the pump. As will be discussed in more detail hereinafter, the inlet plug 166 provides an inlet 168 for admitting production fluid from the well into the pump section 64 of the pump 42.

Rounding out the description of the spent operating fluid system, when the flow through the return tubing 46 is reversed, fluid enters the counterbore 1-40 surrounding the inlet plug 166, and acts upwardly on an annular area of the pump equal to the difference between the areas indicated by the dimensional arrows 170 and 172, thereby unseating the pump and moving it upwardly. The operation of removing the pump 42 from the well in this manner will be described more completely hereinafter in discussing the operation of the present invention.

Considering the flow of production fluid through the bottom-hole assembly 40, interconnecting the sealing collar 68 and the bottom shoe 70 is a pump housing tube 174, this tube being threadedly connected to the lower end of the sealing collar 68 and being inserted into a counterbore 176 therein below the counterbore 86, as shown in FIG. 8. Referring to FIG. 11, the pump housing tube 174 is threaded at its lower end into the upper end of the bottom shoe 70 and extends into a counterbore 178 therein above the counterbore 144. The pump housing tube 174 provides an annular space 180 around the pump section 64 of the pump, this annular space being sealed at its upper end by the O-ring 94, FIG. 8, and at its lower end by the O-ring 148, FIG. 11. The annular space 180 communicates with a production fluid outlet 182, FIG. 8, of the pump 42, whereby production fluid discharged by the pump section 64 of the pump enters this annular space. Referring particularly to FIG.

-11, the lower end of the annular space 180 communicates, 'just above the sleeve 146, with a passage 184 in the bottom shoe 70. This passage communicates with a longi- -tudinal bore 186 into which extends the lower end of a pipe 188. Referring to FIGS. 3 and 8, the pipe 188 ex- 8 tends upwardly through a bore 189 through the sealing collar 68, and is threaded at its upper end, FIG. 5, into the lower end of the upper sealing collar 66 in communication with a longitudinal bore 190 therein. The upper end of the bore 190 communicates with a radial passage 191 which leads to an external annular groove 192 in the sleeve 112, this groove communicating with radial ports 193 leading to an internal annular groove 194 in the sleeve. Registering with the groove 194 and located between the O-rings 114 is an external annular groove 195 in'a fitting 196 which is carried by the pump 42 and which carries the O-rings 114. Radial ports 197 in the fitting 196 connect the groove 195 to an axial bore 198 therein, there being at the upper end of the bore 198 a seat 199 for an upper pump standing valve 200 which fiunotions to prevent backflow of production fluid into the pump 42 when the latter is not completely filled with production fluid. Production fluid flowing upwardly past the standing valve 200 flows through radial ports 201 and 202 into a counterbore 203 in the sealing collar 66 above the bore 106 therein, the lower end of the production tubing being threaded into the counterbore 203. Thus, the bottom-hole assembly 40 establishes fluid communication between the production fluid outlet 182 of the pump section 64 and the production tubing 48, the production fluid flowing upwardly through the relatively large production tubing with a minimum of frictional resistance.

The Pump 42 Considering the pump 42 now in more detail, it includes at its upper end a packer nose assembly comprising a packer mandrel 204 threaded into the fitting 196 to retain the valve seat 199 in this fitting, the radial ports 201 being formed in the packer mandrel. Mounted on the mandrel 204 is a packer cup 205 of a size to make a fluid-tight fit with the inner wall of the production tubing 48 when it is disposed therein, whereby fluid supplied beneath the pump 42 will move the pump upwardly through the production tubing to the surface. However, when the pump is in its operating position wherein the inlet plug 166 is seated on the seat 164, the packer cup 205 is disposed within the counterbore 203, which is sufficiently large that the production fluid can flow upwardly therepast into the production tubing. The packer mandrel 204 terminates at its upper end in a tapered nose 206 engageable by a pump catcher, not shown, carried by a removable closure 207, FIG. 1, mounted on the control device 50.

The lower end of the fitting 196 is threaded into. and forms a closure for the upper end of an engine cylinder 208, this cylinder having threaded into its lowerv end a tube 210 which is threaded onto a valve body 212 of the engine valve 62. Reciprocable in the engine cylinder 208 is an engine piston or plunger 214 having end portions 216 and 218 of reduced diameter which enter recesses 220 and 222, respectively, in the fitting 196 and the tube 210 at the ends of the working and return strokes, respectively, of the engine plunger. The end portions 216 and 218 of the engine plunger are only slightly smaller than the recesses 220 and 222 so that, in effect, dashpots are provided for decelerating the engine plunger at the ends of its working and return strokes.

Referring to FIG. 8 in particular, connected to the lower end of the valve body 212 is a tube 224 onto which is threaded a pump cylinder 226 having the production fluid outlet therein adjacent the upper end thereof. 7 The lower end of the pump cylinder 226 has threaded thereinto a fitting 228 which carries the O-ring 148 and into the lower end of which is threaded the inlet plug 166. When the pump 42 is in operation, production fluid from the well flows through the standing valve assembly 154 and the inlet 168 into the fitting 228. Clamped between the inlet plug 166 and the fitting 228 is a' seat 230 for a lower pump standing valve 232, which is shown as a simple ball valve. Upward movement of the standing valve 232 off its seat is limited by a stop 234 which is pressed into the fitting 228 and which is provided with apertures 236 for production fluid flow therethrough into the pump cylinder 226. The purpose of the standing valve 232 is to prevent backfiow out of the pump cylinder 226 without necessitating seating of the standing valve 156, the latter preferably having a delayed seating action as more fully discussed in my aforementioned copending application.

Reciprocable in the pump cylinder 226 is a pump piston or plunger 240 which is connected to the engine plunger 214 by a piston rod 242. As more fully discussed herein-after, the piston rod 242 extends through the engine valve 62 and controls the operation thereof, the piston rod acting as a pilot valve.

Referring particularly to FIG. 12, the pump plunger 248 includes a plunger body 244 into the upper end of which the piston rod 242 is threaded. Threaded onto the lower end of the plunger body 244 is a fitting 246 having silver soldered therein a seat 248 for a working valve 250, shown as a simple ball valve. Upward movement of the working valve 250 is limited by a stop 252 which is clamped between the fitting 246 and the lower end of the plunger body 244, and which is provided with apertures 254 therethrough for flow of production fluid upwardly into a longitudinal passage 256 through the plunger body. The upper end of the passage 256 communicates with radial ports 258 through which production fluid may flow into the pump cylinder 226 above the pump plunger 240. As will be apparent, during the working stroke of the pump plunger 240, which is the upward stroke in the particular embodiment illustrated, the working valve 250 closes so that production fluid above the pump plunger 240 is displaced upwardly through. the standing valve 200, production fluid from the well simultaneously being drawn into the lower end of the pump cylinder through the standing valves 156 and 232. During the return stroke of the pump plunger 240, which is the downward stroke thereof in the particular construction illustrated, the working valve 250 opens and the standing valve 232 closes so that production fluid is displaced from the lower end of the pump cylinder 226 into the upper end thereof past the working valve 250 and through the apertures 254, the passage 256 and the ports 258. During the return stroke, the standing valve 156 remains open due to the delayed action discussed in detail in my aforementioned copending application. The standing valve 280 also tends to remain open during the return stroke, except when the pump cylinder 226 is not completely filled.

Considering the fluid pressures which produce the reciprocatory movement of the piston means 58, com prising the plungers 214 and 24%) and the piston rod 242, the upper end of the engine plunger 214 is always exposed to the fluid pressure in the return tubing 46 through the port means 120, FIGS. 5, 23 and 24. The annular area at the upper end of the pump plunger 240, equal to the difference between the area of the pump plunger and the area of the rod 242, is always exposed to the fluid pressure in the production tubing 48 through the production fluid outlet 182, FIGS. 8, 23 and 24. The lower end of the pump plunger 240 is also exposed to the pressure in the production tubing 48 during its return, or downward, stroke due to opening of the working valve 250 and closing of the standing valve 232, and is exposed to the pressure of the fluid in the well during its working, or upward, stroke. The annular area at the lower end of the engine plunger 214, equal to the difference between the area of the engine plunger and the area of the rod 242, is exposed to the pressure in the supply tubing 44 during the working, or upward, stroke and is exposed to the pressure in the return tubing 46 during its return, or downward, stroke. The manner in which the pressures in the supply and return tubings 44 and 46 are applied to the lower end of the engine plunger 214 by the engine valve 62 will be considered in detail hereinafter.

Considering how the return stroke of the piston means 58 is produced, it will be apparent that, since the pressure in the return column is applied to both ends of the engine plunger 214 during the return stroke, the engine plunger has applied thereto a downward pressure force equal to the product of the return column pressure and the area of the rod 242. Similarly, since, during the return stroke, the pressure in the production column is applied to both ends of the pump plunger 240, the pump plunger has applied thereto an upward pressure force equal to the product of the production column pressure and the area of the rod 242. Expressed more simply, the pressure in the return tubing 46 acts downwardly on an effective area equal to the area of the rod 242, and the pressure in the production tubing 48 acts upwardly on an effective area equal to the area of the rod. Thus, by maintaining the pressure in the return tubing 46 higher than the pressure in the production tubing 48, the return stroke of the piston means 58 will be effected when the lower end of the engine plunger 214 is exposed to the pressure in the return tubing by the engine valve 62. As hereinbefore indicated, the pressure in the return tubing may be maintained higher than the pressure in the production tubing by means of the control device 50 at the surface, and the pressure differential between the return and production columns can be varied at the surface. Consequently, the speed of the return stroke of the piston means 58 is controllable at the surface independently of the speed of the working stroke, and other factors, and may be any value whatsoever, as desired, which is an important feature of the invention.

The Engine Valve 62 Turning now to a consideration of the environment of the engine valve 62, the rod 242, as previously indicated, extends through the engine valve. The rod 242 is sealed at each end of the engine valve 62 by means of floating bushings, the floating bushings at the upper end of the engine valve being designated by the numeral 264 and those at the lower end thereof being designated by the numeral 262. As best shown in FIG. 13, the lowermost of the floating bushings 260 is seated against a bushing 264 inserted into the upper end of the valve body 212, which is tubular. The uppermost of the floating bushings 260' is seated against a bushing 266 pressed into the tube 210, this bushing having an internal thread for engagement with a tool for removing it from the tube 210. Thus the floating bushings 260 are retained between the bushings 264 and266. Similarly, the floating bushings 262 are retained between a bushing 268, FIG. 13, inserted into the lower end of the valve body 212 and a bushing 270, FIG. 8, pressed into the tube 224 to which the pump cylinder 226 is connected. For convenience in manufacture, the bushings 262, 268 and 270 are identical to the bushings 260, 264 and 266, respectively, although, as will become apparent, the two sets of bushings, except for their rod sealing functions, perform somewhat diiferent functions.

Considering the engine valve 62 itself, the engine valve is hydraulically operated under the control of the piston rod or pilot valve 242 to connect the lower end of the engine cylinder 208 alternately to the supply and return tubings 44 and 46 to produce reciprocatory movement of the piston means 58. The valve 62 governs with a three-speed action during the working stroke of the pump 42 and has a single-speed action during the return stroke thereof. Except for some important differences in mechanical structure, the engine valve 62 is basically quite similar to and operates in substantially the same manner as the engine valves disclosed in my Patents Nos. 2,311,- 157 and 2,580,657. Consequently, in order to avoid unnecessary descriptive matter in this specification, the structure and operation of the engine valve 62 will be described herein only in a general way, except for the important differences in mechanical structure mentioned, which" will be described in detail hereinafter.

Referring particularly to FIGS. and 16 of the drawings, and also to FIGS. 23 and 24 thereof, the engine valve 62 includes a tubular valve member 272 which is disposed in the tubular valve body 212 and which encircles the rod 242, the valve member 272 having a sliding fit with both the valve body and the rod. Externally, the valve member 272 is of uniform diameter and, internally, the valve member is provided with a minor diameter 274 and a major diameter 276, the minor diameter being such as to receive the rod 242 with a sliding fit. With this construction, a differential-area valve member results, having a large annular area 278 at its lower end, and smaller inner and outer areas 280 and 282, respectively, at its upper end. The areas 280 and 282 are preferably equal and each is preferably equal to one-half the area 278, the area 280 being equal to the difference between the cross-sectional areas of the rod 242 and the bore 276 and thus including the area of the lower side of an internal annular channel 312 in the valve member 272 which is described hereinafter. The inner and outer annular areas 280 and 282 are separated from each other by a floating sleeve or bushing 284 which has a sliding fit with the rod 242 and a sliding fit with the major diameter 276 of the valve member 2.72. Thus the differential-area valve member 272 is similar in principle to those disclosed in my Patents Nos. 2,081,220, 2,081,223, 2,134,174 and 2,204,120, except that, instead of being externally stepped, it is internally stepped and the resulting areas are separated by the floating sleeve 284, which are important features of the invention.

As shown in FIGS. 13 to 15, 23 and 24, the operating fluid exhaust 124 in the valve body 212 communicates with the outer annular area 282 of the valve member 272 at all times, irrespective of whether the valve member is in its lower position, as shown in FIGS. 13 and 23, or in its upper position, as shown in FIGS. 14 and 24, downward movement of the valve member being limited by engagement thereof with the bushing 268 and upward movement of the valve member being limited by engagement thereof with the floating sleeve 284. Thus the outer annular area 282 is constantly exposed to the pressure in the return tubing 46. The operating fluid intake 82 is in constant communication with the inner annular area 280 through an external annular channel 286 and radial ports 288 in the valve member. Consequently, the valve member 272 is constantly biased downwardly by the pressure in the return column acting on the outer annular area 282 and the pressure in the supply column acting on the inner annular area 280, these areas being separated by the floating sleeve 284, as hereinbefore discussed. Accordingly, the valve member 272 may be moved into its lower position, as shown in FIGS. 13 and 23, by connecting the large area 278 at the lower end thereof to the return column, and the valve member may be moved to its upper position, as shown in FIGS. 14 and 24, by connecting the large annular area 278 to the supply column. The manner in which this is accomplished will be described hereinafter.

It is important to note that, during the upward or working stroke of the piston means 58, the valve member 272 is in its upper position and, during the downward or return stroke of the piston means, the valve member 272 in its lower position, except for the final increments of upward and downward movement of the piston means. Consequently, during the upward or working stroke, friction between the rod 242 and the valve member 272 biases the valve member into its proper operating position, which is its upper position in this instance. Similarly, during the downward or return stroke, friction between the rod 242 and the valve member 272 biases the valve member downwardly into its proper operating position, which is the lower position thereof in this case. Consequently, there is no necessity for opposing friction between the rod 242 and the valve member 272 with fluid pressure, except at the extreme ends of the working and return strokes, which is an important feature of the invention.

Considering how the foregoing is accomplished, FIGS. 13 and 23 of the drawings illustrate the positions of the rod 242 and the valve member 272 when the piston means 58 is at the extreme upper end of its stroke. Under such conditions, the valve member 272 has moved downwardly preparatory to beginning the downward, or return, stroke of the piston means. The upper end of the valve member 272 uncovers ports 290, FIGS. 13, 15, 18 and 23, and places them in communication with the operating fluid exhaust 124 through the annular space around the floating sleeve 284. The ports 290 communicate with passages 292 which extend upwardly through the valve body 212 and communicate at their upper ends with an annular space 294 around the floating bushings 260. Referring to FIG. 8, the annular space 294 communicates at its upper end with longitudinal grooves 296 extending through the bushing 266 and leading to the interior of the tube 210. The interior of this tube communicates at its upper end with the lower end of the engine cylinder 208. Consequently, the lower end of the engine plunger 214 is placed in communication with the operating fluid exhaust 124, whereby to produce the downward or return stroke of the piston means 58 by means of the pressure differential between the return and production tubings 46 and 48, as hereinbefore discussed. Thus the valve member 272, when in its lower position, as shown in FIGS. 13 and 23 of the drawings, produces the downward or return stroke of the piston means.

When the valve member 272 is in its upper position, as shown in FIGS. 14 and 24, it produces the working or upward stroke of the piston means 58. Considering how this is accomplished, it will be noted that the annular channel 286 in the valve member 272 connects the operating fluid intake 82 to the ports 290, whereby operating fluid flows upwardly through the passages 292, the annular space 294, the grooves 296, and the interior of the tube 210 into the lower end of the engine cylinder 208 to act on the lower end of the engine plunger 214. Thus the working or upward stroke of the piston means is produced when the valve member is in its upper position.

The foregoing description of the manner in which the valve member 272 effects the return and working strokes is general only. For a complete description applied to a basically similar'valve member, attention is directed to my aforementioned Patents Nos. 2,311,157 and 2,580,657.

Considering now how the lower end of the valve member 272 and is alternately connected to the supply and return tubings 44 and 46, to move the valve member to its upper and lower positions, respectively, attention is again directed to FIGS. 13 and 23 of the drawings. As previously indicated, FIGS. 13 and 23 show the relative positions of the rod 242 and the valve member 272 at the extreme upper end of the travel of the piston means 58, the valve member 272 having moved downwardly to initiate the downward or return stroke. However, just before the rod 242 reached the upper end of its stroke, the valve member 272 was in its upper position to effect the working stroke. As the rod 242 approached the upper end of its travel, longitudinal grooves 298 therein placed the annular space around the rod below the valve member 272 in communication with the operating fluid exhaust 124 through a port 300 in the bushing 268, a port 302 in the valve body 212, passages 304 in the valve body, ports 306 in the valve body, and passages 308 in the valve body. Thus the operating fluid under pressure from the supply column constantly acting on the inner annular area 280 of the valve member 272 moves the valve member into its lower position, as shown in FIGS. 13 and 23, this occurring by the time the rod 242 reaches the upper end of its travel. Thereupon the downward or return stroke commences The valve member is moved upwardly into its upper position, shown in FIGS. 14 and24, in asomewhat simi' lar manner. In FIGS. 14 and 24 the rod 242 has reached the lower limit of its travel and the valve member 272 has moved upwardly into its upper position to initiate the upward stroke. Just before the rod 242 reached the lower end of its travel, grooves 310 therein connected the internal annular channel 312 in the valve member 272, which internal annular channel always contains operating fluid under high pressure due to its communication with the operating fluid intake 82 through the ports 233 and the channel 286, with ports 314, FIG. 22, in the valve member. The ports 314 extend outwardly into communication with an external annular channel 316 in the valve member which, when the valve member was in its lower position, registered with ports 318 in the valve body 212. The ports 318 communicate with longitudinal passages 320 in the valve body which lead downwardly to radial ports 322 extending inwardly into communication with the lower end of the valve member. Thus operating fluid under pressure from the supply tubing 44 is delivered to the lower end of the valve member 272 to act on the annular area 278 thereof, thereby initiating upward movement of the valve member toward its upper position in preparation for the upper or working stroke. It should be pointed out that the valve member 272 is provided with ports 321 therein which communicate with the operating fluid exhaust 124, through a passage 319, the passages 292 and the ports 290, when the valve member is in its lower position, FIG. 13, to hold the valve member down. Since the ports 321 communicate with the lower end 278 of the valve member 272, through passages 323, it is necessary that the pressure drop through the ports 321 greatly exceed the pressure drop through the grooves 310 in the valve rod 242. Thus, when the grooves 310- connect the lower end 278 of the valve member 272 to the operating fluid intake 82 as hereinbefore described, sufiicient pressure is applied to the lower end of the valve member to initiate upward movement thereof. The upward movement of the valve member 272 is completed by applying the operating fluid pressure to the area 278 of the valve member through other passages which it is thought unnecessary to describe herein.

The foregoing is only a general description of the manner in which the valve member 272 is moved between its upper and lower positions. For a complete description, attention is again directed to my aforementioned Patents Nos. 2,311,157 and 2,580,657.

Another important feature of the invention resides in the mechanical structure of the valve body 212. As shown throughout FIGS. 13 to 16 and 18 to 22 of the drawings, the'valve' body 212 includes an inner sleeve 324 and an outer sleeve 326 secured together in a fluid-tight manner, the aforementioned O-rings 92 and 94 encircling the inner sleeve 324 and engaging the ends of the outer sleeve 326. Various ones of the passages in the valve body 212, such as the hereinbefore described passages 3133 and 320, are located at the interface between the inner and outer sleeves, and are preferably grooves formed in the inner sleeve 324 for manufacturing convenience. These grooves in the inner sleeve 324 are closed by the outer sleeve 326 to form the desired passages, such as the passages 308 and 320. In order to provide a fluid-tight fit between the inner and outer sleeves 324 and 326, the inner sleeve may be pressed into the outer sleeve, or the outer sleeve may be shrunk onto the inner sleeve. This construction for the valve body 212 greatly simplifies manufacture and results in a minimum number of drilled ports and passages, which is an important feature of the invention.

Operation Considering now the over-all operation of the invention, it will be assumed that the tubing system 38 and the bottom-hole assembly 40 have been run into the well, but that the pump 42 has not yet been installed in its operating position. In order to install the pump 42, the closure 207 is removed and the pump is inserted into the upper end of the production tubing 48. By means of the control device 50, operating fluid from the supply pipe 52 is directed into the production tubing 48 above the pump to displace the pump downwardly into its operating position, any fluid in the production tubing below the pump being displaced upwardly to the surface through the supply and return tubings 44 and 46. Ultimately, the pump 42 enters the bottom-hole assembly 40 and seats on the seat 164 provided by the standing valve assembly 154. When the pump 42 is in its operating position, the O-rings 114, 92, 94 and 14S engage the respective sleeves 112, 88, and 146, and the packer cup 205 is disposed within the enlarged counterbore 203. Under such conditions, the production fluid inlet 168 communicates only with the Well, the production fluid outlet 182 communicates only with the production tubing 48, the operating fluid intake 82 communicates only with the supply tubing 44, and the port means 120 and the operating fluid exhaust 124 communicate only with the' return tubing 46. Thus the pump 42 is now ready for operation, being held on its seat 164 by the pressure in the production column thereabove. The production column pressure acts downwardly on the entire areaof the'pump 42, whereas the return column pressure acts upwardly on only the diflerence between the areas 172 and 170, FIG. 11. Thus there is a pressure force differential acting downwardly to hold the pump 42 on its seat.

After the pump is in its operating position, the control device 5 0 is operated to connect the supply, return and production tubings 44, 46 and 48 to the supply, return and production pipes 52, 54 and 56, respectively, with a back pressure applied to the return tubing 46 to maintain the pressure therein higher than that in the production tubing 48. This maintains the pressure differential between the return and production tubings 46 and 48 necessary to eflect the return stroke of the piston means 58.

Considering the operating fluid flow through the pump 42,. the operating fluid underpressure flows downwardly through the supply tubing 44, through the upper sealing collar 66-, and through the pipe '72, the bore 74, the passage 78, and the main bore 80 into the operating fluid intake 820i the pump. The piston rod or pilot valve 242 and the differential-area valve member 272 cooperate to connect the lower end of the engine plunger 214 to the operating fluid intake 82 and the operating fluid exhaust 124 alternately. The exhaust 124 communicates with the return tubing 46 through the counterbore 122 and the annular space 118, FIG. 8, and through the bore 106, the passage 104, the bore 102, the passage and the bore 98, FIG. 6. The upper end of the engine cylinder 208 is in constant communication with the return tubing 46 through the port means 120, the annular space 118, and the bore 106, FIG. 5, and through the passage 104, the bore 102, the passage 100 and the bore 98, FIG. 6. Thus the upper end of the engine plunger 214 is constantly exposed to the pressure in the return tubing 46, while the lower end of the engine plunger is alternately exposed to the pressures in the supply and return tubings 44 and 46.

The upper end of the pump plunger 240 is constantly exposed to the pressure in the production tubing 48 through the production fluid outlet 182 and the annular space 180, FIG. 8, through the passage 184, the bore 186 and the pipe 188, FIG. 11, and, FIG. 5, through the passage 191, the groove 192, the ports 193, the grooves 194 and 195, the ports 197, the bore 198, the standing valve 200, the ports 201 and 202, and the counterbore 203. The lower end of the pump plunger 240 is alternately exposed to the pressure in the well and to the pressure in the production column. Exposure of the lower end of the pump plunger to the fluid pressure in the Well takes place through the fitting 228, the apertures 236, the standing valve 232, which opens during the working stroke of the piston means 58, and through the inlet 168 and the standing valve assembly 154, all as shown in FIG. 11. During the return stroke, the standing valve 232 closes and the working valve 250 carried by the pump plunger opens to connect the lower end of the pump plunger to the upper end thereof, thereby exposing the lower end of the pump plunger to the production column pressure in the same manner as the upper end of the pump plunger.

Under the foregoing conditions, when the lower end of the engine plunger 214 is connected to the supply tubing 44 by the engine valve 62 in the manner described, the piston means 58 is moved upwardly to accomplish the Working stroke thereof. Under such conditions production fluid is discharged into the production tubing 48 along the avenue described, and production fluid from the well is drawn into the lower end of the pump cylinder along the avenue described. At the end of the working stroke, the engine valve 62 connects the lower end of the engine plunger 214 to the return tubing 46 as described, and the standing valve 232 closes and the working valve 250 opens to expose the lower end of the pump plunger 240 to the pressure in the production tubing 48. Thus, under such conditions, the upper and lower ends of the engine plunger 214 are exposed to the return column pressure and the upper and lower ends of the pump plunger 240 are exposed to the production column pressure. The return column pressure acts downwardly on the piston means on an effective area equal to the area of the piston rod 242, while the production column pressure acts upwardly on the piston means on the same effective area. Since the return column pressure is maintained at a higher value than the production column pressure by applying a back pressure to the return tubing 46 at the surface by means of the control device 50, a downward pressure force differential acts on the piston means 58 to effect the return stroke thereof, which is an important feature of the in vention. By accomplishing the return stroke of the piston means in this manner, the speed of the return stroke may be controlled at the surface independently of all other factors so that the speed of the return stroke may be any desired value, which is an important feature. For example, the speed of the return stroke may be equal to, or greater or less than, the speed of the working stroke.

It should be noted that due to the hereinbefore described operation of the engine valve 62, the valve member 272 is in its upper position during the upward, working stroke of the piston means 58, and is in its lower position during the downward, return stroke thereof, except for the final increments of movement of the piston means. Consequently, during the working and return strokes, friction between the rod 242 and the valve member 272 urges the valve member into its proper operating position, which is an important feature.

When it is desired to remove the pump 42 from the well for repair or replacement, the control device 50 is operated to connect the supply pipe 52 to the return tubing 46 and to close the supply tubing 44, the production tubing 48 remaining connected to the production pipe 56. Under such conditions, operating fluid under pressure flows downwardly through the return tubing 46 to the lower end of the pump 42 by way of the bore 98, the passage 100, the bore 102, the passage 104, the bore 106 and the annular space 118, FIG. 6, the counterbore 122, the passage 126, the bore 128, the passage 130, the bore 132 and the pipe 134, FIG. 10, and the bore 136 and the passage 138, FIG. 11. The pressure of the operating fluid thus delivered to the lower end of the pump 42 acts upwardly on an annular area thereof equal to the difference between'the areas 172 and to unseat the pump, this pressure acting on the entire area of the pump the moment the pump has been unseated, backfiow into the well being prevented by the standing valve assembly 154. By the time the pump has been moved upwardly sufliciently that the various O-rings on the exterior thereof disengage the corresponding sleeves, the packer cup 205 enters the production tubing 48 to provide a fluid-tight seal to prevent bypassing the pump 42. Continued delivery of operating fluid below the pump through the return tubing 46, or through both the supply and return tubings 44 and 46, results in upward displacement of the pump through the production tubing 48 to the surface. When the pump 42 arrives at the surface, the tapered nose 206 at the upper end of the packer mandrel 204 engages the pump catcher, not shown, carried by the removable closure 207, whereupon the pump may be removed from the production tubing 48 by removing the closure.

Although I have disclosed an exemplary embodiment of the invention, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment, and that various individual features of the invention may be utilized in other, different embodiments, all without departing from the spirit of the invention as defined by the claims hereinafter appearing.

I claim as my invention:

1. In a fluid operated engine valve, the combination of:

(a) a valve body having a cylindrical valve chamber therein;

(b) a tubular, internally-stepped, differential-area valve member reciprocable in said valve chamber;

(c) said valve member having two different inside diameters adjacent the respective ends thereof;

(d) said different inside diameters providing said valve member with a large, annular first area at one end thereof, a small, outer, annular second area at the other end thereof, and a small, inner, annular third area intermediate the ends thereof and facing in the same direction as said annular second area;

(e) a tubular cylindrical member in said valve member and having an outside diameter substantially equal to the larger of said inside diameters of said valve member;

(1) said tubular cylindrical member separating said annular second and third areas;

(g) means for constantly applying a low pressure to one of said annular second and third areas;

(h) means for constantly applying a high pressure to the other of said annular second and third areas;

(1) means for alternately applying low and high pressures to said annular first area; and

(j) the means last mentioned including a valve rod extending through said tubular cylindrical member and said valve member.

2. In a fluid operated engine valve, the combination of:

(a) a valve body having a cylindrical valve chamber therein;

(b) an internally-stepped, differential-area valve mem ber reciprocable in said valve chamber;

(c) said valve member having an axial bore therein having an inner end;

(d) said valve member having a large, first area adjacent one end thereof, a small, outer, annular second area adjacent the other end thereof, and a small, inner, third area at the inner end of said axial bore and facing in the same direction as said second area;

(e) a cylindrical member in said axial bore and having an outside diameter substantially equal to the diameter of said axial bore;

(f) said cylindrical member separating said second and third areas;

(g) means for constantly applying a low pressure to one of said second and third areas;

(h) means for constantly applying a high pressure to the other of said second and third areas; and

15 (1') means for alternately applying low and high pressures to said first area. 3. In a fluid operated engine valve, the combination (a) a valve body having a cylindrical valve chamber therein;

(b) a tubular, internally-stepped, differential-area valve member reciprocable in said valve chamber;

(0) said valve member having two difi'erent inside diameters adjacent the respective ends thereof;

(d) said different diameters providing said valve member with a large, annular first area at one end thereof, a small, outer, annular second area at the other end thereof, and a small, inner, annular third area intermediate the ends thereof and facing in the same direction as said annular second area;

(e) a tubular cylindrical member in said valve member and having an outside diameter substantially equal to the larger of said inside diameters of said valve member;

(1) said tubular cylindrical member separating said annular second and third areas; and

(g) means for applying an alternating fluid pressure to one of said areas, including a valve rod extending through said tubular cylindrical member and said valve member.

4. In a fluid operated engine valve, the combination (a) a valve body having a cylindrical valve chamber therein;

(b) an internally-stepped, differential-area valve member reciprocable in said valve chamber;

(0) said valve member having an axial bore therein having an inner end;

(d) said valve member having a large, first area adjacent one end thereof, a small, outer, annular second area adjacent the other end thereof, and a small, inner, third area at the inner end of said axial bore and facing in the same direction as said second area;

(e) a cylindrical member in said axial bore and hav ring an outside diameter substantially equal to the diameter of said axial bore;

(1) said cylindrical member separating said second and third areas; and

(g) means for applying an alternating fluid pressure to one of said areas.

5. In an engine valve, the combination of:

(a) a valve body having a cylindrical valve chamber therein;

(b) a tubular, internally-stepped, differential-area valve member reciprocable in said valve chamber;

(c) said valve member having tWo different inside diameters adjacent the respective ends thereof;

(d) said different diameters providing said valve member with a large, annular first area at one end thereof, a small, outer, annular second area at the other end thereof, and a small, inner, annular third area intermediate the ends thereof and facing in the same direction as said 'annular second area;

(2) a tubular cylindrical member in said valve member and having an outside diameter substantially equal to the larger of said inside diameters of said valve member;

(7) said tubular cylindrical member separating said annular second and third areas; :and

(g) a valve rod extending through said tubular cylindrical member and said valve member.

6. In an engine valve, the combination of 2 (a) 'a valve body having a cylindrical valve chamber therein;

(11) an internally-stepped, differential-area valve member reciprocable in said valve chamber;

(c) said valve member having an axial bore therein having an inner end;

(d) said valve member having a large, first area adjacent one end thereof, a small, outer, annular second area adjacent the other end thereof, and a small, inner, third area at the inner end of said axial bore and facing in the same direction as said second area;

(e) a cylindrical member in said axial bore and having an outside diameter substantially equal to the diameter of said axial bore; and

(f) said cylindrical member separating said second and third areas.

7. A fluid operated engine valve according to claim 1 wherein said tubular cylindrical member is axially slidable in said valve member and on said valve rod.

References Cited in the file of this patent UNITED STATES PATENTS 647,671 De Lew Apr. 17, 1900 2,048,550 Helenberg July 21, 1936 2,555,755 Moore June 5, 1951 2,690,192 Danhardt Sept. 28, 1954 2,821,141 Sargent Jan. 28, 1958 3,009,480 Miller Nov. 21, 1961 

1. IN A FLUID OPERATED ENGINE VALVE, THE COMBINATION OF: (A) A VALVE BODY HAVING A CYLINDRICAL VALVE CHAMBER THEREIN; (B) A TUBULAR, INTERNALLY-STEPPED, DIFFERENTIAL-AREA VALVE MEMBER RECIPROCABLE IN SAID VALVE CHAMBER; (C) SAID VALVE MEMBER HAVING TWO DIFFERENT INSIDE DIAMETERS ADJACENT THE RESPECTIVE ENDS THEREOF; (D) SAID DIFFERENT INSIDE DIAMETERS PROVIDING SAID VALVE MEMBER WITH A LARGE, ANNULAR FIRST AREA AT ONE END THEREOF, A SMALL, OUTER, ANNULAR SECOND AREA AT THE OTHER END THEREOF, AND A SMALL, INNER, ANNULAR THIRD AREA INTERMEDIATE THE ENDS THEREOF AND FACING IN THE SAME DIRECTION AS SAID ANNULAR SECOND AREA; (E) A TUBULAR CYLINDRICAL MEMBER IN SAID VALVE MEMBER AND HAVING AN OUTSIDE DIAMETER SUBSTANTIALLY EQUAL TO THE LARGER OF SAID INSIDE DIAMETER OF SAID VALVE MEMBER; (F) SAID TUBULAR CYLINDRICAL MEMBER SEPARATING SAID ANNULAR SECOND AND THIRD AREAS; (G) MEANS FOR CONSTANTLY APPLYING A LOW PRESSURE TO ONE OF SAID ANNULAR SECOND AND THIRD AREAS; (H) MEANS FOR CONSTANTLY APPLYING A HIGH PRESSURE TO THE OTHER OF SAID ANNULAR SECOND AND THIRD AREAS; (I) MEANS FOR ALTERNATELY APPLYING LOW AND HIGH PRESSURES TO SAID ANNULAR FIRST AREA; AND (J) THE MEANS LAST MENTIONED INCLUDING A VALVE ROD EXTENDING THROUGH SAID TUBULAR CYLINDRICAL MEMBER AND SAID VALVE MEMBER. 